1. Field of the Invention
This invention relates to rotatable valve structures but is more particularly directed to a floating valve assembly for ball valves responsive to variations in pressures of fluids being controlled by the valve assembly.
2. Description of the Prior Art
All rotatable valve assemblies utilizing ball or spherical surfaced valves consist of a pair of valve seats engaging the valve on opposite sides thereof with seals interposed between the valve and valve seats. The amount of pressure or force being imposed at the seals by the valve seats against the ball valve determines the effectiveness of the seal against leakage. However, the greater this pressure is, the more difficult it will be to actuate or rotate the valve from one position to the other.
The conventional rotatable valve devices provide valve seats that are fixed in relation to the ball valve. Consequently, in order to prevent the possibility of leakage of fluids past rotatable valves when in a closed position, the valve seats are secured tightly against the valve. In so doing, the ball valve becomes difficult to rotate to its various positions especially if the valve is manually actuated. Therefore, it is important that the valve seats be tightened against the valve only to the degree that the seals therebetween prevent any leakage when the valve is in a closed position. In addition if there is an increase in fluid pressure after the valve seats had been adjusted for a lesser pressure, a leakage would possibly occur. Other conditions that may cause rotatable valves to leak occur after a considerable passage of time or use of the valve when the seals become worn, misshapen or lose their resiliency so that the valve seats are no longer sufficiently tightened against the valve to render the seals effective to prevent leakage therealong. By the use of a floating valve seat, the present invention contemplates avoiding the above objections to the conventional fixed valve seals for ball valves.